The United States said the latest launches were of Scud-class, short-range ballistic missiles and violated U.N. Security Council resolutions that call on North Korea to abandon its ballistic missile program.
"We urge North Korea to refrain from provocative actions that aggravate tensions and instead focus on fulfilling its international obligations and commitments," State Department spokeswoman Jen Psaki told reporters in Washington. "Scud missile launches are a violation of these U.N. Security Council resolutions."
However, North Korea routinely test-fires short-range missiles, and outside analysts say the recent launches weren't expected to raise tensions, as was the case last spring when North Korea repeatedly threatened to launch nuclear wars following its third nuclear test in February last year. Recently, North Korea has pushed for improved ties with South Korea and taken conciliatory gestures, including rare reunions of Korean War-divided families last month.
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On Monday, two projectiles blasted from the North's east coast flew about 500 kilometers (310 miles) before landing in the high seas, South Korean Defense Ministry spokesman Kim Min-seok told reporters.
South Korea is trying to confirm what exactly North Korea fired on Monday based on the speed and trajectory of the projectiles, but an initial investigation showed they were missiles, suspected to be Scud-series, a Defense Ministry official said, speaking on condition of anonymity in line with department rules.
He said the North Korean missiles flew past a South Korean air defense identification zone and landed in the waters below the Japanese defense zone.
Kim said the launches were made without a prior notice. He described them as a provocation posing a serious threat to international aviation and maritime navigations and civilian safety. "North Korea is doing an act of double standard by taking a peace offensive ostensibly, but later launching reckless provocative acts," he said.
Chang Yong Seok of the Institute for Peace and Unification Studies at the Seoul National University said that the launches appeared to be part of North Korean military training aimed at coping with the South Korea-U.S. drills. He said that tensions could be heightened if North Korea tested a longer-range missile capable of hitting Japan or the U.S. territory of Guam.
Analysts say the North's recent charm offensive toward South Korea is largely aimed at helping lure foreign investment and aid to help revive the country's troubled economy.
The two Koreas are divided along the world's most heavily fortified border since the 1950-53 Korean War ended with an armistice, not a peace treaty. About 28,500 American troops are deployed in South Korea to deter potential aggression from North Korea. South Korea and the U.S. have said they have no intentions of invading North Korea and that their ongoing springtime drills are defensive in nature.
—By The Associated Press